android - 原生 actionbar.show() 和 hide() 动画的时长是多少

Question

我想在操作栏动画时做一些动画。但是，我不知道操作栏动画的持续时间。

Answer 1

不幸的是， native 操作栏动画时间似乎在 Android source code 中进行了硬编码 在 4.1 版之后(没有属性，没有维度，没有方法)并且设置为 250ms:

actionbar.hide()方法在Android 4.1/4.4中的实现示例:

public void doHide(boolean fromSystem) {
    if (mCurrentShowAnim != null) {
        mCurrentShowAnim.end();
    }

    if (mCurWindowVisibility == View.VISIBLE && (mShowHideAnimationEnabled
            || fromSystem)) {
        mContainerView.setAlpha(1);
        mContainerView.setTransitioning(true);
        AnimatorSet anim = new AnimatorSet();
        float endingY = -mContainerView.getHeight();
        if (fromSystem) {
            int topLeft[] = {0, 0};
            mContainerView.getLocationInWindow(topLeft);
            endingY -= topLeft[1];
        }
        ObjectAnimator a = ObjectAnimator.ofFloat(mContainerView, View.TRANSLATION_Y, endingY);
        a.addUpdateListener(mUpdateListener);
        AnimatorSet.Builder b = anim.play(a);
        if (mContentAnimations && mContentView != null) {
            b.with(ObjectAnimator.ofFloat(mContentView, View.TRANSLATION_Y,
                    0, endingY));
        }
        if (mSplitView != null && mSplitView.getVisibility() == View.VISIBLE) {
            mSplitView.setAlpha(1);
            b.with(ObjectAnimator.ofFloat(mSplitView, View.TRANSLATION_Y,
                    mSplitView.getHeight()));
        }
        anim.setInterpolator(AnimationUtils.loadInterpolator(mContext,
                com.android.internal.R.interpolator.accelerate_cubic));
        anim.setDuration(250);
        anim.addListener(mHideListener);
        mCurrentShowAnim = anim;
        anim.start();
    } else {
        mHideListener.onAnimationEnd(null);

这也发生在 Lollipop 上:

public void doHide(boolean fromSystem) {
        if (mCurrentShowAnim != null) {
            mCurrentShowAnim.end();
        }
        if (mCurWindowVisibility == View.VISIBLE && (mShowHideAnimationEnabled
                || fromSystem)) {
            mContainerView.setAlpha(1);
            mContainerView.setTransitioning(true);
            AnimatorSet anim = new AnimatorSet();
            float endingY = -mContainerView.getHeight();
            if (fromSystem) {
                int topLeft[] = {0, 0};
                mContainerView.getLocationInWindow(topLeft);
                endingY -= topLeft[1];
            }
            ObjectAnimator a = ObjectAnimator.ofFloat(mContainerView, View.TRANSLATION_Y, endingY);
            a.addUpdateListener(mUpdateListener);
            AnimatorSet.Builder b = anim.play(a);
            if (mContentAnimations && mContentView != null) {
                b.with(ObjectAnimator.ofFloat(mContentView, View.TRANSLATION_Y,
                        0, endingY));
            }
            if (mSplitView != null && mSplitView.getVisibility() == View.VISIBLE) {
                mSplitView.setAlpha(1);
                b.with(ObjectAnimator.ofFloat(mSplitView, View.TRANSLATION_Y,
                        mSplitView.getHeight()));
            }
            anim.setInterpolator(AnimationUtils.loadInterpolator(mContext,
                    com.android.internal.R.interpolator.accelerate_cubic));
            anim.setDuration(250);
            anim.addListener(mHideListener);
            mCurrentShowAnim = anim;
            anim.start();
        } else {
            mHideListener.onAnimationEnd(null);
        }
    }

在 4.1 之前(例如 4.0.1) 没有硬编码的持续时间值(实际上根本没有值)，无论如何您可以使用反射来访问第一个动画后 Animator 的持续时间。字段访问如下:

private Animator mCurrentShowAnim;

我知道这不是一个完整的答案，但我认为它可能会有帮助。